Direct Ingot Making of Titanium by Electro-winning from Molten Salt, Using Metal Pool of Titanium

本课题的研究目的是开发以金属钛池为阴极的钛电积直接制锭工艺。利用电渣重熔装置，对电渣重熔过程进行了热分析、电极反应机理和沾污机理的研究。TiO_2的加入对体系的电子传导影响很小，可以忽略不计。用钢棒操作电渣重熔装置，阐明了电渣重熔过程中金属熔池形状与电流-电压条件的关系。在ESR的情况下，金属池不能在远高于纯钛熔点的温度下获得。可以看出，钛的熔点由于氧的吸收而升高。因此，在单电池操作中，整个装置的气氛，特别是阴极部分的气氛，必须是内部的。 ...更多信息 CaO-CaF_2-TiO_2渣系的最大阴极电流效率为12%，阳极电流效率远低于100%。其原因是：1）Ca的金属雾的形成及其在阳极处的再氧化，2）Ti与Ti^<4+>反应形成Ti^<2+>及其在阳极处的再氧化，以及3）Ca的量不足形成Ti^<2+>及其在阳极处的再氧化。因此，控制好电极间距和TiO_2含量是十分重要的。将70 g电沉积物和c.a.阴极电流效率可达60%。其原因可能是由于添加Al以保持较高的熔渣温度，以及Al存款对渣中Ti^4+起还原作用。该工艺有利于钛铝合金的生产，但由于电沉积层中含有大量的铝，不利于纯钛的生产。它由一个阳极槽和一个阴极槽组成，两个槽之间用熔盐桥连接。采用该装置可使阴极与阳极之间保持较长的距离，从而获得较大的电流效率和较好的电沉积质量。该装置成功地运行了。因此，所提出的方法是非常有前途的。上述结果发表在6篇论文中。少

The purpose of the present research project is to develop the direct ingot making process of titanium by electro-winning of titanium, where the metal pool of titanium is used as the cathode. By using ESR unit, the thermo-analysis of process, electrode reaction mechanism and contamination mechanism were examined.At first, the electrical conductivity of CaO-CaF_2-TiO_2 slag was measured. The effect of TiO_2 addition was so small that the electronic conduction could be neglected. Thus, the addition of TiO_2 to the slag was possible at relatively large amount.By operating ESR unit with steel rod, the relation between shape of metal pool and current-voltage condition was clarified. In the case of ESR, the metal pool could not be obtained at far higher temperature than the melting point of pure titanium. It was seen that the melting point of titanium rose by the absorption of oxygen. Thus, the atmosphere of the whole apparatus, especially, cathode part, must be innert.In the single cell oper … More ation with CaO-CaF_2-TiO_2 slag, the maximum cathodic current efficiency was 12%, and the anodic current efficiency was far less than 100%. The reasons must be 1) formation of metal fog of Ca and its re-oxidation at the anode, 2) formation of Ti^<2+> by the reaction of Ti with Ti^<4+> and its re-oxidation at the anode, and 3) formation of Ti^<2+> by the insufficient amount of Ca and its re-oxidation at the anode. Thus, it is important to control the electrodes distance properly and to control the TiO_2 content properly.On the contrary, by the addition of Al_2O_3 to the slag, c.a. 70 g of electro-deposit and c.a. 60% of cathodic current efficiency were obtained. The reasons must be that the temperature of molten slag should be kept higher temperature by the addition, and that the Al deposit should act as the reductant of Ti^<4+> in the slag. This process is good for producing Ti-Al alloy, but not good for producing pure Ti, because the electro-deposit contained much Al.On the base on the above results, the new apparatus was designed. It consists of twin cell, one of which is anode cell and the other, cathode cell, connected with molten salt bridge. By this apparatus, the distance between cathode and anode can be kept long, resulting in the larger current efficiency and better quality of electro-deposit. The apparatus was successfully operated. Thus, the proposed process is very promising. The above results are published in 6 papers. Less